In the production of elongated structural shapes from extruded materials, usually extruded plastics, the extruder can be provided upstream of a calibrator and a saw, the calibrator serving to impart final dimensions and configurational nuances to the extruded body and the saw serving to cut the extruded body, arriving in a continuous form, into predetermined lengths. The extrusion apparatus or lines of this type can be provided with a haul-off, takeoff or hauler apparatus which is generally provided with upper and lower track assemblies between which the extrudate is gripped and which advances the extrudate along the line.
The extrudate is referred to variously as an extruded body, a profile or a workpiece and, in the production of window frame extrusions or the like, frequently two such extruded bodies must be gripped simultaneously between the upper and lower track assemblies.
The track assemblies comprise sprockets or rollers which are spaced apart by the lengths of the respective assembly on supports or frames, generally comprising two elongated members extending in the longitudinal direction, and an endless track or caterpillar passing around the sprockets or rollers, driven by a motor connected to a sprocket at one end of the assembly and carrying pads which engage the extruded article. Thus the pads of the upper and lower track assemblies grip the extruded profile between them and drag the extruded profile from the extruder which is located upstream of the hauler through any processing stations therebetween.
It has been found that certain types of extruded profiles cannot be uniformly gripped by conventional track assemblies which are usually oriented with respect to one another in a fixed relationship. For example, the pads of one or another of the track assemblies may not be oriented with respect to a particular shape so that the extruded profile can be effectively engaged, and as a result, the workpiece can be damaged. In addition, in the production of window profiles, when two such profiles are extruded simultaneously and both are to be uniformly gripped utilizing conventional hauler apparatus in which the orientations of the upper and lower track assembly can be fixed with respect to one another, it is frequently found that one of the profiles will be gripped with a greater force than the other and uniform products will not be obtained.
In general, therefore, it can be said that conventional hauler apparatus utilizing track assemblies with fixed orientations, at least with respect to longitudinal axes of these assemblies, may result in excessive defects in the product and reduced productivity of the overall apparatus.
The problem is especially pronounced when the extruded workpiece has a nonsymmetrical cross section and especially surfaces which are inclined or angled in a nonsymmetrical manner.